1. Field of the Invention
The present invention relates to an electro-photographic apparatus employing an electro-photographic system.
2. Description of the Related Art
In an electro-photographic apparatus such as a laser printer or a copying machine, a structure including a heating roller and a pressurizing member as a fixing device for fixing an unfixed toner image on a recording medium such as paper or OHP has been known. Among the fixing devices of this type, there has been known the fixing device which is configured that three pressurizing members are provided relative to the endless belt for the purpose of prolonging heating and pressurizing time for the recording medium for attaining high-speed fixation (Refer to JP-A-2004-29611, for example).
According to the related art, the fixing device includes the heating roller having a heat source incorporated therein, the endless belt wound around the heating roller, and the three pressurizing members for pressurizing the endless belt into contact with the heating roller, wherein total pressure and peak pressure of one of the three pressurizing members at a second position from upstream in a conveying direction of the recording medium are set to be maximal.
However, there is no disclosure, in the related art, about condition of the pressure in a direction of a rotation axis of the heating roller, which would affect quality of picture or conveyance of the recording medium. There has been such a problem that in case where irregularity has occurred in pressurizing force of the pressurizing member influenced by variations in production, printing unevenness may occur, which may result in degradation of printing quality.